Thread cutting die



Jan. 15, 1935. 1,988,046

L. NIKOLOFF THREAD CU'TTING DIE Original Filed Oct. 15, 1930 2 Sheets-Sheet l 66 68 47 65 I zwenior:

' Laban/Niko Zojf,

Jan. 15, 1935. N o o 1,988,046

THREAD CUTTING DIE Original Filed Oct. 15, 1930 2 Sheets-Sheet 2 67 f gos 78 Inven/Zor: Lwzzew/Nv'fizaiajf.

Patented Jan. 15, 1935 UNITED STATES PATENT OFFICE THREAD CUTTING DIE Luben Nikoloff, Boston, Mass.

Claims. (Cl. -126) This invention relates-to a thread-cutting die having. several novel features, including, first, means .for adjusting the body, and consequently the chasers, to vary the diameter of the screw to 5 be out; second, a blankguide which is adjustable axially with relation to the body, and in the case of an adjustable body is self-adjusting to compensate for adjustment of the body; and third, improved handles by which the die-stock is manipulated. There are disclosed in this application other novel features which are not claimed herein, namely, first, thread-cutting chasers which may be removed when worn or broken, and replaced by new ones; second, hard inserts set into the body of the die-stockto receive the wear of the chasers; and, third. 9. bevel at the first end of the chaser to bevel off the end of the blank or stock, in case the latter is somewhat over-size. The first two of these other features are the subject matter of myoriginal application, Ser. No. 488,833, filed October 15, 1930, of which-the present application is a division. g I v The invention will bestbe understood by reference to the following description, when taken in connection with the accompanying drawings of three illustrative embodiments thereof, while its scope will be pointed out more particularly in theappended claims. I

In the drawings: Fig. 1 is an elevation, partly in vertical section, of one form or embodiment of the invention;

Fig. 2 is an. elevation at an enlarged scale of a portion of Fig. 1; Fig.3 is a sectional view on line 33 of Fig. 2; Fig. 4 is a sectional view on line 4 -4 of Fig.2; 7

Fig. 5 is 'a sectional view on Fig. 2;

Fig. 6 is a perspective view of one of the thread-cutting chasers shown in Figs. 1 to 5, inclusive;

Fig. 7 is an elevation, partly in vertical section. of a second form or embodiment of the invention;

Fig. 8 is an elevation, at an enlarged scale, of a portion of Fig. 7; v

Fig. 9 is a sectional view, on line 9-9 of line 5 5 of Fig. 8;

Fig. 10 is a sectional view on line 10-40 of Fig. 8;

Fig. 11 is a sectional view on line 11-11 of as Fig. 8;

Fig. 12 is a sectional view on line 12-12 of Fig. 8; and b,

Fig. 13 is a perspective view of one of the thread-cutting'chasers shown in Figs.- '7 to 12, inclusive;

Referring to the formof the invention which is illustrated in.Figs. 1- ,to-6, inclusive, ofithe drawings, and. having reference at first more particularly to Fig. 1-, there is shown a; threadcutting die comprising :a body. 21, provided with a blank-receiving opening .22, v and a plurality .of chaser-receiving s1ots23. In thisv example, there are four of these slots, each of which receives a thread-cutting chaser .24, though the number will depend somewhatv upon: the diameter, of the stock or blank to be threaded. The number will vary from three to sixor more in practice, but of course the-designer the body or holder mayhave to be varied to suit. the number of chasers. v

One important feature of my invention which characterizes all three forms is that the body and the chasers have interengagingmeans restraining the chasers against. movement lengthwise of the axis of the die, and providing for attachment of each chaser to the .body by movement of the-chaser, first inione; direction and then in another direction toa position in which the chaser is interengaged with the body, and restrained against movement lengthwise of the axis. To this end, in the form shown in Figs. 1 to 6, inclusive, the slots are radial, and the body is provided with a; plurality of pairs of grooves 25,-one pair associated witheach slot, the two grooves of each pair leading' laterally in opposite directions, respectively, from-the associated slot, said grooves extending lengthwise of the'axis of the die. 3

In this form, each chaser is provided with two setsof oppositely projecting tongues-(best shown in Fig. 6), interengaged with the body, each set oftongues on eachchaser comprising two pairs of tongues 26 and two-pairs of tongues 27, four overlying one face of the body and four overlying the opposite face. The width of each tongue 26 in a generally radial direction is somewhat less than the width of each groove 25, and the tongues 26 and 27 are separated by spaces 28, whose width is somewhat greater than'the distance between the groove 25 and the central opening 22. As a consequence, each chaser is detachable from the body by sliding radially along its slot toward the central opening to bring the two pairs of tongues 26 into registration witl e pect ve g oov 5 on opposite.

sides of the slot, and to bring the other two pairs of tongues 27 into registration with the central opening. This movement unlocks the chaser, and permits the latter to slide in its slot lengthwise of the axis of the die. During this sliding movement, the tongues 26 of one pair slide through the grooves 25, while the tongues 27 of one pair pass through the central opening 22. Thus, any or all of the chasers when worn or broken may be removed and replaced by new ones.

As the body will be made of a comparatively soft grade of steel, capable of flexing in the manner presently to be described, without danger of crystallizing and cracking, the body may be, and herein is, provided with sets of relatively hard inserts, such as cylindrical pins, comprising two pairs of pins 29 and two pairs of pins 30, to receive the wear of the chasers. Each tongue 26 overlies a pin 29, and each tongue 2'7 overlies a pin 30, as will be evident from a comparison of Figs. 2 and 5.

To retain the chasers in their proper positions intheir respective slots, there is associated with each chaser a suitable retainer, herein a screw 31 extending loosely through a radial hole 32 in'the body, and havingscrew-threaded engagement with a threaded hole 33 (best shown in Fig'. 6) in'the chaser. By first removing these screws, the chasers maybe dismounted from the body in the manner hereinbefore described.

Another feature of the invention now to be described is means for adjusting the body, and consequently the chasers, to vary the diameter of the screw to be out. To this end, in the form of the invention illustrated in Figs. 1 to 6, inclusive, the body is rendered expansible and contractible by providing the same with two slots 34 (see Fig. 2), leading in opposite directions from the central opening 22, or it may be considered that there is a single slot interrupted by the central opening. To increase the flexibility of the holder, each slot at its outer end terminates in an opening 35, herein cylindrical. Thus,the body is quite thin on opposite sides of these openings, and is capable of bending with the requisite degree of freedom. The body is also equally thin at the outer ends of the chaser-receiving slots 23, and is capable of flexing at these points as well.

Adjustment of the holder by flexing the same is conveniently accomplished by the use of tapered adjusting screws 36 (best shown in Fig. 3), threaded into the body. These screws may be and herein are provided with hexagonal sockets 37, toreceive 'a tool :by means of' which they may be 'turned.' By turning the screws in the proper direction, the body may be expanded or allowed tocontract at will, thereby furnishing an adjustment to vary the diameter of the screw to be cut by the chasers.

'To prevent the adjustment from being disturbed accidentally and to cooperate with the screws 3'7 to clamp the chasers in their slots by reducing the width of the latter, I have provided two clamping screws 38, associated with the slots 34, respectively, and adapted to clamp the body about the adjusting screws 36, to prevent rotation of the latter. As shown, each clamping screw is provided at one end with a head- 39, and extends, first loosely through an opening 40 at one side of the slot 34, then across the slot, then into a screw-threaded opening 41, with which it has screw-threaded engagement. As a measure of safety, to prevent the clampin screw from being screwed so far as to cause danger of breakage of the body, and further, as a means to prevent loss of the clamping screws, each in the present example is provided with a safety stop 42, normally separated from the adjacent side of the body by a space 43. Each stop is conveniently secured to its screw by providing the latter with a reduced portion 44 to receive the stop, and the outer end of the screw is headed over or riveted, as at 45, to hold the stop in place.

After the tapered screws 37 have been adjusted to vary the diameter of the screw to be cut by the chasers, the clamping screws 38 are turned in the proper direction to clamp the screws 37, thus to retain their adjustment and further to flex the body at the outer ends of the body. The screws 37 then serve as fulcrums during the flexing action and the metal between the side of the slot 23 and the adjacent side of the slot 34 is rocked about the associated screw 27 as a fulcrum toward the opposite side of the slot 23 while the metal at the outer ends of the slot 23 flexes. This action reduces the width of the slot 23, and, as a result, the clearance is taken up and the chaser is clamped so that it cannot move either endwise or sidewise.

Another feature of the invention which may be termed a blank guide will now be described, reference being had to Fig. 4. This guide is for the purpose of guiding the blank or stock, and holding the same properly centered with relation to the chasers. As shown, the guide comprises a plate 46, provided with an aperture 47 whose diameter is such that the blank or stock just slides freely through it, and is accurately centered. This plate is conveniently mounted for adjustment on the body by providing the latter with holes 48 lengthwise of the axis of rotationof the die to receive slidable pins 49, which may be clamped in any desired position within the range or adjustment by set screws 50, herein having knurled heads 51 to enable them to be turned with the fingers.

One of the pins 49 is permanently and rigidly affixed to the plate 46, as by providing the same with a reduced portion 52 passed through the plate, and riveted as at 53. Inasmuch as this particular die has an adjustable body, the remaining pin 49 is self-adjusting to compensate for adjustment of the body. This is conveniently accomplished in the present example by providing the remaining pin with a reduced portion 54, which extends through a radial, elongated slot 55 in the plate 46, the reduced portion extending thence through and secured as by riveting at 56 to a block 57, which is slidable radially in a groove 58 provided in the plate. Thus, the pin is capable of moving radially with relation to the plate when the body is being adjusted.

, Referring to Fig. 5, it will be observed that the chaser is provided with, not only the usual chamfer represented by the line A--A, but also a bevel, represented by the line B--B (which may be either round or straight), herein round, the purpose of which is to bevel off the end of the blank or stock, in case the latter is somewhat over size. This prevents the tearing and spoiling of threads, which sometimes occurs when the stock is somewhat larger than it should be.

In this form of the invention, the body is provided with handles 59, which are integral therewith and of cylindrical form. As shown, these of' the first form, but in this form,,each handle handles-are lightened by'drilling holes ('see the left-handportion of Fig. 1) lengthwise of the handles. When the handles are short, it is desirable to provide the outer end of each with a rounded terminal portion in the form of a cap 61 to prevent injury to the palms of the hands. This cap is conveniently attached to the handle byproviding the cap with a tapered portion 62, which merges into the cylindrical surface of the handle; and is conveniently secured to the latter, as by welding.

The second form or-embodiment of the invention will now be described, reference being had toFigs. 7 to 13, inclusive. In this form, there is abody 63, having a central opening 64 to receive the blank or stock, and a plurality of chaser-receiving slots 65, which as shown are four in number, and radially disposed. Each of these slots receives a thread-cutting chaser 66, which, like the chasers of the first form, is interengaged with the body; In this form, however;" thechaser is flush at its ends with the faces of the'b'ody (see Fig. 11). Interengage- :ment in the chaser and the body in this case is had" by providing the chaser with'two sets of tonguesorteeth 67 and 68 (see Figs. 12 and 13), interengaged with correspondingly-shaped teeth ion the body. The latter is provided with lateral grooves 69, one associated with each slot 65, and extending lengthwise of the axis of thedie, the width of each groove in aradial direction being somewhat greater than the width of the tongues or teeth 67; 'The chaser is provided with a groove or space 70, between" its two sets of tongues or teeth, and. the width of this space is somewhat greater than the distance from the groove 69' to the central opening 64. As a result,

the chaser may be'dismounted from the body by sliding the chaser'radially inward to bring the tongues or teeth '67 into registration with the groove '69,and to bring the tongues or teeth 68 into registration with' the central openingfil, thus unlocking the chaser from the body and permitting the chaser then to slide in the slot lengthwise of the axis'of the die. To facilitate machining the tongues or teeth in the body, the latter as shown is provided with grooves 71, adjacent the outer ends of the slots 65 (see Fig.

8); Here, as in the first form, the chasers are normally secured in place by radial screws 72.

. I In this form of the invention, as in the first, the body' is adjustable; but in this form, the means of adjustment while having a general resemblance to the first form, differs somewhat in detail, more specifically by the employment of a single'adjusting screw and a singleclamp- -ing screw. Referring to Fig. 8, the body is rendered flexible by providing the same with two slots 73 and 74, the former being straight and the latter having an oblique portion 75, which extends to the side of the body. The slot 73 terminates at its outer end in an opening 76 to increase the flexibility. In this case, as already intimated, there is a single tapered adjusting screw 77, threaded into the body, and there is a single clamping screw 78. As these screws are like the corresponding screws of the first form, it is deemedunnecessary to describe them in detail.

is detach'ably secured to the body by providing the latter with a reduced threaded portion 81,

upon which is screwed a thimble 82, the latter having a reduced portion 83 inserted into the tubular handle, and suitably securedtherein as by welding at 84.

Having thus described certain embodiments of the invention, but without limiting myself thereto, what I claim and desire by Letters Patent to secure is:

1. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, and means which renders said body expansible and contractible about said opening, a blank guide provided with a blank-receiving opening,

and means providing an adjustable connection to permit said blank guide to be adjusted axially toward and from said body, said means comprising a plurality of parallel pins extending lengthwise-of the axis of said opening, and set screws threaded into said body and engaging said pins,'respectively, said guide being secured to one of said pins and having a loose connection with the other to render the same self-adjusting to compensate for expansion and contraction of 'said body.

2. In a thread-cutting die, the combination of a body provided with a blank-receiving opening and with a plurality of chaser-receiving openings, a plurality of chasers received in said chaser-receiving openings, respectively, means to secure said chasers in said chaser-receiving openings, a blank guide provided with a. blank-receiving opening, and "means including a plurality of rods and clamping screws associated with said rods, respectively, and providing an adjustable expansibleand contractible and which also. renders saidfchaser-receiving openings expansible and contractible, a plurality of chasers received in said chaser-receiving openings, respectively,-

and 'means for causing expansion of said blankreceiving opening and simultaneously'the contraction of'said chaser-receiving openings to cause said chasers to be gripped by the sides of said chaser-receiving openings.

4. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, 'a plurality of chaser-receiving openings, and a slot between said chaser-receiving openings and communicating with said blank-receiving opening, said slot rendering said blank-receiving opening expansible and contractible and also rendering said chaser-receiving openings ex- "p'ansible and contractible, a pluralityof'chasers received in said chaser-receiving openings, respectively, a screw which expands said slot in width, thereby expanding said blank-receiving opening, and means cooperating with said screw to cause the contracting of said chaser-receiving openings to grip said chasers.

5. In a'thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and a slot between said chaser-receiving openings and communicating with said blank-receiving open ing, said slot rendering said blank-receiving opening expansible' and contractible and also rendering said chaser-receiving openings expansible and contractible, a plurality of chasers received in said chaser-receiving openings, respectively, a screw which expands saidslot in width, thereby expanding said blank-receivin opening, and means cooperating with said screw to cause the contracting of said chaser-receiving openings to gripv said chasers, said screw being threaded into and interengaged with said body at opposite sides, respectively, of said slot and preventing relative movement of said sides length- ,wise of the axis of said blank-receiving opening.

6; In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and a slot which renders said blank-receiving opening preserve adjustment of the second-mentioned means.

'7. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and a slot which renders said blank-receiving opening expansible and contractible and which also renders said chaser-receiving openings expansible and contractible, a plurality of chasers received in said chaser-receiving openings, respectively,

meansfor causing expansion of said blank-receiving opening, means cooperating with the first-mentioned means to cause the contraction of saidchaser-receiving openings, thereby to ,cause said chasers to be gripped by the sides of said chaser-receiving openings, and means for preventing expansion of said blank-receiving opening beyond the amount established by adiustment of the first-mentioned means.

8. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and a slot between said chaser-receiving openings and communicating'with said blank-receiving opening, said slot rendering said blank-receiving opening expansible' and contractible and also rendering said chaser-receiving openings expansibie and contractible, a plurality of chasers received in said chaser-receiving openings, respectively, a screw which expands said slot in width, thereby expanding said blank-receiving opening, and means cooperating with said screw to cause contracting of said chaser-receiving openings to grip said chasers, the second-mentioned meansbeing constructed and arranged to preserve adjustment of said screw.

9. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiver openings, and a slot between said chaser-receiving openings and communicating with said blank-receiving opening, said slot rendering said blank-receiving opening expansible and contractible and also rendering said chaser-receiving openings expansible and contractible, a plurality of chasers received in said chaser-receiving openings, respectively, a screw whichiexpands said; slot in width, therebyexpanding said blank-receiving "opening, means cooperating with said screw to cause contracting of said chaser-receiving openings to grip said chasers, and means for preventing such expansion of the width of said slot beyond a predetermined amount.

10. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and a slot between said chaser-receiving openings and communicating with said blank-receiving opening, said slot rendering said blank-receiving opening expansible and contractible and also rendering said chaser-receiving openings expansible and contractible, a plurality of .chasers received in said chaser-receiving openings, respectively, a screw which expands said slot in width, thereby expanding said blank-receiving opening, and means cooperating with said screw to cause the contracting of said chaser-receiving openings to grip said chasers, said means tending to contract said slot, thereby to grip said screw and to preserve its adjustment.

11. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings at whose outer ends said body is flexible to enable said chaser-reeeiving openings to be contracted,

,and a slot which renders said body expansible about said blank-receiving opening, a plurality of chasers received in said chaser-receiving openings, respectively, means to cause said slot to expand to move said chasers outwardly and to maintain the faces of said body at opposite sides of said slot in alignment, and means cooperating with the first-mentioned means to flex said body at the outer ends of said chaser-receiving openings and to cause the portions of said body between said slot and said chaser-receiving openings to reduce the size of the latter and to clamp said chasers in said-chaser-receiving openings.

12. In-a thread-cutting die, the combination of a-body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and-two slots communicating with said blank receiving opening, a plurality of chasers received in said chaser-receiving openings, respectively, and means comprising two tapered screws associated with said slots, respectively, threaded into said body at opposite sides of said'respective associated slots and extending lengthwise of the axis, of said blank-receiving opening to cause increase of the width of said slots and to cause a thrust of portions of said body against said chasers.

13. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, and two slots communicating with said blank-receiving opening, a plurality of chasers received in said chaser-receiving openings, respectively, and

means comprising two tapered screws associated with said slots, respectively, threaded into said body at opposite sides of said respective associated slots and extending lengthwise of the axis of said blank-receiving opening to cause increase of the width of said slots and to cause a thrust of portions of said body against said chasers, said means comprising two clamping screws associated with said tapered screws, respectively, and extending transversely of said axis normally to prevent rotation of said clamping screws by clamping portions of said body about said tapered screws.

14. In a thread-cutting die, the combination of a body provided with a blank-receiving opening, a plurality of chaser-receiving openings, two opposite slots which render said body expansible and contractible about said blank-receiving opening, and two apertures associated with said slots, respectively, each aperture being intersected by its said associated slot, each aperture being formed with a screw thread partly at one side of the slot and partly at the other side of the slot, and each aperture having a tapered formation, a plurality of chasers received in said chaser-receiving openings, re-

spectively, and means associated with each of said slots, at opposite sides of said blank-receiving opening, to increase the widths of said slots, said means comprising screws associated with said slots, respectively, extending lengthwise of the axis of said blank-receiving opening and threaded into said screw threads at opposite sides of their respective, associated slots, said screws having tapered formations engaging said tapered formations of said apertures.

LUBEN NIKOLOFF. 

